Integrated circuit structure with semiconductor devices and method of fabricating the same

ABSTRACT

An integrated circuit (IC) structure includes a substrate having several regions, several semiconductor devices formed at the substrate and respectively within the regions, and an ultra-deep (UD) trench isolation structure formed in the substrate. The substrate has a top surface and a bottom surface oppositely, and the UD trench isolation structure formed in the substrate surrounds peripheries of each of the regions for structurally and physically isolating the semiconductor devices within different regions. The UD trench isolation structure penetrates the substrate by extending from the top surface of the substrate to the bottom surface of the substrate.

This application claims the benefit of People's Republic of Chinaapplication Serial No. 201710036189.3, filed Jan. 17, 2017, thedisclosure of which is incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The disclosure relates in general to an integrated circuit (IC)structure and a method of fabricating the same, and more particularly toan IC structure with semiconductor devices and a method of fabricatingthe same.

Description of the Related Art

Reduction of feature size, improvements of the rate, the efficiency, thedensity and the cost per integrated circuit (IC) unit are the importantgoals in the semiconductor technology. The electrical properties of thedevice have to be maintained even improved (ex: with the decrease of thesize) to meet the requirements of the commercial products inapplications. The layers and components with defects, such as positionmisalignment, incomplete profiles and insufficient distance between thecomponents, would have considerable effects on the electricalperformance of the device.

For example, during fabricating a conventional IC structure, it ispreferably to provide a sufficient distance (ex: over one hundred ofmicrometers) between a low-side region and a high-side region on thesubstrate, each region containing a lateral-diffusion MOS transistor,for sustaining large voltage drop and maintaining the electricalcharacteristics of the IC structure; however, this would limit the sizereduction of the IC structure.

SUMMARY

The disclosure is directed to an integrated circuit (IC) structure withsemiconductor devices and a method of fabricating the same. Thesemiconductor devices formed within the different regions are isolatedby an ultra-deep (UD) trench isolation structure.

According to one aspect of the present disclosure, an integrated circuit(IC) structure is provided, comprising a substrate having a top surfaceand a bottom surface oppositely, and the substrate comprising aplurality of regions; plural semiconductor devices formed at thesubstrate and respectively within the plurality of regions; and anultra-deep (UD) trench isolation structure formed in the substrate andsurrounding peripheries of each of the plurality of regions forstructurally and physically isolating the semiconductor devices withindifferent regions of the plurality of regions. The UD trench isolationstructure penetrates the substrate by extending from the top surface ofthe substrate to the bottom surface of the substrate.

According to one aspect of the present disclosure, a method offabricating an IC structure, comprising: providing a substrate having aplurality of predetermined regions; forming an ultra-deep (UD) trenchisolation structure in the substrate and surrounding peripheries of eachof the plurality of predetermined regions, wherein the UD trenchisolation structure extends from a top surface of the substratedownwardly; and lapping backside of the substrate until a lower surfaceof the UD trench isolation structure being exposed on a bottom surfaceof the substrate, wherein the bottom surface is opposite to the topsurface of the substrate.

The disclosure will become apparent from the following detaileddescription of the preferred but non-limiting embodiments. The followingdescription is made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A simply depicts a top view of an integrated circuit (IC)structure having a substrate according to one embodiment of the presentdisclosure.

FIG. 1B simply depicts a cross-sectional view of the substrate of FIG.1A along a cross-sectional line 1B-1B.

FIG. 2 depicts a cross-sectional view of a substrate and semiconductordevices formed within the regions of the substrate according to oneembodiment of the present disclosure.

FIG. 3 depicts a cross-sectional view of another substrate andsemiconductor devices formed within the regions of the substrateaccording to one embodiment of the present disclosure.

FIG. 4 depicts a cross-sectional view of a further substrate andsemiconductor devices formed within the regions of the substrateaccording to one embodiment of the present disclosure.

FIG. 5A-FIG. 5B illustrate a method of fabricating an IC structureaccording to one embodiment of the present disclosure.

DETAILED DESCRIPTION

In the embodiments of the present disclosure, an integrated circuit (IC)structure with semiconductor devices and a method of fabricating thesame are provided. The semiconductor devices formed within the differentregions of a substrate are isolated by an ultra-deep (UD) trenchisolation structure. According to embodiment, the UD trench isolationstructure penetrates the substrate by extending from the top surface ofthe substrate to the bottom surface of the substrate. For an ICstructure in the application, the embodied design having an UD trenchisolation structure provides a great isolation between the semiconductordevices within the different regions of the substrate. Also, theembodied design having an UD trench isolation structure achieves a sizereduction of the IC, thereby saving the manufacturing cost.Additionally, in some embodiments, some regions in the semiconductordevices such as a first region A₁ adjacent to a high-side region A_(HS)and/or a second region A₂ adjacent to a low-side region A_(LS) areimplemented by using at least one of vertical double-diffused metaloxide semiconductor (VDMOS) transistors, which significantly enhancesthe heat dissipations of the semiconductor devices, thereby improvingthe reliability of the semiconductor devices and prolonging theoperation life of the IC structure.

Embodiments are provided hereinafter with reference to the accompanyingdrawings for describing the related configurations of integrated circuit(IC) structures and semiconductor devices formed within the regions of asubstrate. Related structural details, such as layers and spatialarrangement, are further described in the embodiments as below. However,the present disclosure is not limited thereto. It is noted that not allembodiments of the invention are shown. The identical and/or similarelements of the embodiments are designated with the same and/or similarreference numerals. Also, it is noted that there may be otherembodiments of the present disclosure which are not specificallyillustrated. Modifications and variations can be made without departingfrom the spirit of the disclosure to meet the requirements of thepractical applications. It is also important to point out that theillustrations may not be necessarily be drawn to scale. Thus, thespecification and the drawings are to be regard as an illustrative senserather than a restrictive sense.

Moreover, use of ordinal terms such as “first”, “second”, “third” etc.,in the specification and claims to describe an element does not byitself connote any priority, precedence, or order of one claim elementover another or the temporal order in which acts of a method areperformed, but are used merely as labels to distinguish one claimelement having a certain name from another element having the same name(but for use of the ordinal term) to distinguish the claim elements.

FIG. 1A simply depicts a top view of an integrated circuit (IC)structure having a substrate according to one embodiment of the presentdisclosure. FIG. 1B simply depicts a cross-sectional view of thesubstrate of FIG. 1A along a cross-sectional line 1B-1B. In oneembodiment, the substrate 10 of an IC structure has several regions,several semiconductor devices (such as metal oxide semiconductor devicesor the likes) respectively formed within the regions of the substrate10. As shown in FIG. 1A, an ultra-deep (UD) trench isolation structure12 is formed in the substrate 10 and surrounds the periphery of each ofthe regions. The UD trench isolation structure 12 penetrates thesubstrate 10 by extending from the top surface 10 a to the bottomsurface 10 b of the substrate 10, as shown in FIG. 1B. According to theembodiment, the UD trench isolation structure structurally (andphysically) isolates the semiconductor devices within different regionsof the regions.

Since the UD trench isolation structure 12 penetrates through thesubstrate 10, it provides great isolation between the semiconductordevices within the different regions. According to the embodiment, adepth T_(UD) of the UD trench isolation structure 12 is substantiallyequal to a thickness T_(S) of the substrate 10. In one embodiment, thedepth T_(UD) of the UD trench isolation structure 12 is at least 60 μmor more, such as in a range of about 60 μm to about 65 μm. Also, in oneembodiment, a width of the UD trench isolation structure is at least 1μm or more, such as in a range from 2 μm to 3 μm.

Moreover, as shown in FIG. 1B, the UD trench isolation structure 12 hasan upper surface 12 a and a lower surface 12 b positioned oppositely,wherein the lower surface 12 b is exposed on the bottom surface 10 b ofthe substrate 10, and the upper surface 12 a is exposed on the topsurface 10 a of the substrate 10. Also, in one embodiment, the uppersurface 12 a of the UD trench isolation structure 12 is substantiallyaligned or coplanar with the top surface 10 a of the substrate 10, andthe lower surface 12 b of the UD trench isolation structure 12 issubstantially aligned or coplanar with the bottom surface 10 b of thesubstrate 10. Additionally, the UD trench isolation structure 12comprises an insulating material, and material examples includenitrides, oxides, and a combination thereof, such as silicon nitride orsilicon oxide, etc. However, the disclosure is not limited to thenumerical values and the exemplified materials as listed above.

In an IC structure of the practical application, the substrate 10 has atleast a high-side region A_(HS) and a low-side region A_(LS), and thehigh-side region A_(HS) and the low-side region A_(LS) can be positionedadjacently and apart from each other by the UD trench isolationstructure 12 of the embodiment for saving the space of the substrate 10.As shown in FIG. 1A, the peripheries of the high-side region A_(HS) andthe low-side region A_(LS) are surrounded by the UD trench isolationstructure 12 of the embodiment. In this embodiment, the high-side regionA_(HS), the low-side region A_(LS), a first region A₁, a second regionA₂ and a logic region A_(LC) are exemplified for illustrating one ofregion arrangements of the substrate 10, as shown in FIG. 1A. However,it is noted that the region arrangements of the substrate 10 are notlimited to the exemplification of FIG. 1A. The sizes, relative positionsand numbers of the possible regions of a substrate in which thesemiconductor devices are formed can be varied and determined accordingto the actual needs or requirement of the practical application.

FIG. 2 depicts a cross-sectional view of a substrate and semiconductordevices formed within the regions of the substrate according to oneembodiment of the present disclosure. In FIG. 2, the cross-sectionalview of the substrate is taken from such as the cross-sectional line 2-2in FIG. 1A, to show the semiconductor devices formed within thehigh-side region A_(HS), the low-side region A_(LS), and the logicregion A_(LC). Also, those regions of the substrate 10 comprises a metaloxide semiconductor field effect transistor (MOS transistor)(as thesemiconductor device formed within the region), which has a sourceregion S and a drain region D positioned at two sides of a gate 112.Noted that configurations of the MOS transistors formed within thehigh-side region A_(HS), the low-side region A_(LS) and the logic regionA_(LC) can be modified or changed according to actual needs of thepractical application, and the disclosure is not limited to theconfigurations as shown in FIG. 2.

As shown in FIG. 2, each of the high-side region A_(HS) and the low-sideregion A_(LS) comprises at least one complementarymetal-oxide-semiconductor (CMOS) transistor (i.e. implemented by acombination of a p-channel MOS (PMOS) transistor and an n-channel MOS(NMOS) transistor); in the embodiment, a CMOS transistor formed by ahigh voltage (HV)-PMOS and a HV-NMOS is exemplified as a semiconductordevice formed within the region. Take an n-channel MOS (NMOS) transistorfor example, a NMOS transistor comprises an N++ substrate (i.e.implanted by N++ dopants) 102, an N-Epitaxial (epi) layer 104 on the N++substrate 102, a high voltage P type well (HVPW), a N-drift regionformed within the HVPW, the N+ source regions S and the drain region D,a gate electrode (ex: N+ polysilicon) 112 and a gate oxide 110 disposedunder the N+ polysilicon gate 112, wherein a horizontal channel 114 isdiffused from an edge of the source region S/the drain region D near thegate 112, as shown in FIG. 2. A p-channel MOS (PMOS) transistor adjacentto the NMOS transistor possesses similar structure except for the HVNWin the N-Epitaxial (epi) layer 104, the P type of the dopants for thesource region S/the drain region D and the drift region (P).

As shown in FIG. 1A, a first region A₁ and a second region A₂ arefurther depicted for illustrating one possible region arrangement of thesubstrate 10. The first region A₁ is positioned in the vicinity of thehigh-side region A_(HS) and electrically connected to the high-sideregion A_(HS) (ex: by wires above the substrate 10; and the wires notshown in the figures). The second region A₂ is positioned in thevicinity of the low-side region A_(LS) and electrically connected to thelow-side region A_(LS). In one embodiment, a periphery of the firstregion A₁ is surrounded by the UD trench isolation structure 12, so thatthe first region A₁ can be physically apart from the high-side regionA_(HS) due to the formation of the embodied UD trench isolationstructure 12. Similarly, a periphery of the second region A₂ issurrounded by the UD trench isolation structure 12, so that the secondregion A₂ can be physically apart from the low-side region A_(LS) due tothe formation of the embodied UD trench isolation structure 12. With theUD trench isolation structure 12 of the embodiment, those regions (inwhich the semiconductor devices are formed) can be arranged as close aspossible for reducing the total area of the substrate 10; for example,the smallest distance between two adjacent regions can be equal to thewidth W_(UD) of the UD trench isolation structure 12. In one embodiment,the width W_(UD) of the UD trench isolation structure 12 is in a rangefrom 2 μm to 3 μm. Although the arrangement of the related regions inFIG. 1A is provided by setting the embodied UD trench isolationstructure 12 between each other for greatly reducing the area of thesubstrate 10 (saving space), it is not necessary to implement theembodiment by restricting the region arrangement as shown in FIG. 1A. Itis noted that arrangements of those regions is not limited to theexemplification of FIG. 1, and the sizes and relative positions of thoseregions can be varied and determined according to the actual needs orrequirement of the practical application. According to the embodiment,at least one vertical double-diffused metal oxide semiconductor (VDMOS)transistor can be formed in at least one of the first region A₁ and thesecond region A₂ as a semiconductor device disposed within the relatedregion (i.e. a VDMOS transistor formed in the first region A₁ or in thesecond region A₂). Also, the VDMOS transistor can be configured with aplanar structure or a trench-gate structure.

FIG. 3 depicts a cross-sectional view of another substrate andsemiconductor devices formed within the regions of the substrateaccording to one embodiment of the present disclosure. In FIG. 3, thecross-sectional view of the substrate 10 related to the high-side regionA_(HS), the first region A₁, the second region A₂ and the low-sideregion A_(LS) is taken from such as the cross-sectional line 3-3 in FIG.1A, to show the semiconductor devices formed within the first region A₁and the second region A₂. In FIG. 3, at least a VDMOS transistor with aplanar structure is exemplified as the semiconductor devicesrespectively formed within the first region A₁ and the second region A₂.As shown in FIG. 3, the VDMOS transistor with a planar structure formedwithin the first region A₁ and the second region A₂ may comprise an N++substrate (i.e. implanted by N++ dopants) 102 acting as a drain region,an N-Epitaxial (epi) layer 104 on the N++ substrate 102 (or on the drainregion), a P-body region 106, the N+ source regions 108 formed withinthe P-body region 106, a gate electrode (ex: N+ polysilicon) 112 and agate oxide 110 disposed under the gate 112, wherein a horizontal channel114 is diffused from an edge of the N+ source region 108 near the gate112.

FIG. 4 depicts a cross-sectional view of a further substrate andsemiconductor devices formed within the regions of the substrateaccording to one embodiment of the present disclosure. In FIG. 4, thecross-sectional view of the substrate 10 related to the high-side regionA_(HS), the first region A₁, the second region A₂ and the low-sideregion A_(LS) is taken from such as the cross-sectional line 3-3 in FIG.1A, to show the semiconductor devices formed within the first region A₁and the second region A₂. In FIG. 4, at least a VDMOS transistor with atrench-gate structure is exemplified as the semiconductor devicesrespectively formed within the first region A₁ and the second region A₂.As shown in FIG. 4, the VDMOS transistor with a trench-gate structure(having vertical channel and gate) formed within the second region A₂may comprise an N++ substrate 102 acting as a drain region, anN-Epitaxial (epi) layer 104 on the N++ substrate 102 (/the drainregion), a P-body region 106, the N+ source regions 108 formed withinthe P-body region 106, a gate oxide 110 and a gate structure. The gatestructure extends downwardly from the top surface 10 a of the substrate10, and the gate structure comprises a gate 113 (ex: N+ polysilicon) ina vertical trench T_(ch) and an insulating layer 115 (gate dielectricsuch as oxide) surrounding the gate 113 in the vertical trench T_(ch) tocontrol the current conduction. Because of this configuration of thegate 113 in the vertical trench T_(ch), the gate structure as shown inFIG. 4 is often referred to as a trench gate in which length of the gate113 is controlled by the depth of the vertical trench T_(ch). The depthof the vertical trench T_(ch) would be deep enough to cross the P-bodyregion 106 below the top surface 10 a of the substrate 10. Differentfrom the horizontal channel, the vertical MOSFET configured with atrench-gate structure exists a vertical channel (ex: along the extendingdirection of the vertical trench Tch) diffused from an edge of thesource region 108 near the gate 113, and also conducts the currentvertically.

According to the embodiment, no matter the VDMOS transistor isconfigured with a planar structure or a trench-gate structure, a sourceregion (ex: 108) of the VDMOS transistor formed in at least one of thefirst region A₁ and the second region A₂ of an embodied substrate 10 ispositioned at the top surface 10 a of the substrate 10, and a drainregion (ex: 102) of the VDMOS transistor in one of the first region A₁and the second region A₂ of an embodied substrate 10 is positioned atthe bottom surface 10 b of the substrate 10, thereby effectivelyenhancing the heat dissipations of VDMOS transistor. In one embodiment,a heat sink can be attached on the drain region for directly removingthe heat generated by the VDMOS transistor (/semiconductor device).

Additionally, in one embodiment, a periphery of the logic region A_(LC)(apart from the low-side region A_(LS) and the high-side region A_(HS))can be surrounded by the UD trench isolation structure 12, so that thelogical region A_(LC) is physically apart from the high-side regionA_(HS) and the low-side region A_(LS) by the width W_(UD) of the UDtrench isolation structure 12 for saving the space of the substrate 10,thereby reducing the overall area of an IC structure in the application.Also, at least one low voltage (LV)-MOS transistor is formed in thelogic region A_(LC) Although FIG. 2 exemplifies a MOS transistor formedin the logic region A_(LC), the disclosure is not limited thereto. Theidentical and/or similar elements of the MOS in the logic region A_(LC)and the low-side region A_(LS)/the high-side region A_(HS) aredesignated with the same and/or similar reference numerals, and thedetails of the configurations are not redundantly repeated.

It is noted that the semiconductor devices in each of the regions (ex:the high-side region A_(HS), the low-side region A_(LS), the logicregion A_(LC), the first region A₁ and the second region A₂) are notlimited to the exemplified types of the MOS transistors or the VDMOStransistors as depicted in FIG. 2, FIG. 3 and FIG. 4. Alternatively, thehigh-side region A_(HS) and the low-side region A_(LS) could compriseother types of the semiconductor devices. Also, the first region A₁ andthe second region A₂ could comprise the semiconductor devices asillustrated in the VDMOS transistor configured with a planar structureor a trench-gate structure or other applicable type of gate structure,depending on the practical requirement of the applications. Thus, thedisclosure is not limited to the exemplified configurations.

There could be several ways to form the UD trench isolation structure 12of the embodiment. For example, in one practical manufacturing process,the UD trench isolation structure 12 can be formed by extendeddownwardly from the top surface 10 a of the substrate 10 (wafer) to anultra-deep position in the substrate 10 (wafer); after manufacturing thesemiconductor devices required for the IC structure, the backsidelapping is performed for thinning or removing part of thesubstrate/wafer, so as to expose the lower surface 12 b of the UD trenchisolation structure 12 on the bottom surface 10 b of the substrate 10,and achieving a required thickness of the substrate 10 in the finalproduct of the application. FIG. 5A-FIG. 5B illustrate a method offabricating an IC structure according to one embodiment of the presentdisclosure. As shown in FIG. 5A, a wafer such as a substrate 10′ isprovided, and an ultra-deep (UD) trench isolation structure 12 is formedin the substrate 10′ by surrounding peripheries of each of thepredetermined regions (ex. the high-side region A_(HS)/the low-sideregion A_(LS)/the first region A₁/the second region A₂/the logic regionA_(LC)); meanwhile, the UD trench isolation structure 12 has notpenetrated the substrate 10′. FIG. 5A-FIG. 5B depict the high-sideregion A_(HS), the low-side region A_(LS) and the first region A₁ forillustration. Then, backside lapping of the substrate 10′ is performeduntil a lower surface 12 b of the UD trench isolation structure 12 beingexposed on a bottom surface 10 b of the substrate 10, as shown in FIG.5B; meanwhile, the UD trench isolation structure 12 penetrates thesubstrate 10. Moreover, formation of the semiconductor devices (notshown in FIG. 5A/5B) required at the substrate and respectively withindifferent regions of the predetermined regions can be performed beforeor after lapping the backside of the substrate 10′. For example, thesemiconductor devices can be formed before forming the UD trenchisolation structure 12 as shown in FIG. 5A; or formed after generatingthe UD trench isolation structure 12 as shown in FIG. 5A but beforebackside lapping as shown in FIG. 5B; or formed after backside lappingas shown in FIG. 5B. Therefore, for a final product, the UD trenchisolation structure 12 penetrates the substrate 10 by extending from thetop surface 10 a to the bottom surface 10 b of the substrate (i.e., thelower surface 12 b of the UD trench isolation structure 12 exposed onthe bottom surface 10 b of the substrate 10 as shown in FIG. 5B). Also,the UD trench isolation structure 12 of the embodiment can be formedbefore forming STI loop (before forming the MOS/VDMOS), or in STI loop(after forming the MOS/VDMOS). The disclosure has no particularlimitation to the manufacturing process.

According to the aforementioned descriptions, the IC structure of theembodiment(s) possesses many advantages. According to the embodieddesign, since the UD trench isolation structure 12 penetrates throughthe substrate 10 (i.e. having a depth T_(UD) equal to the thicknessT_(S) of the substrate 10), it provides great isolation between thesemiconductor devices within the different regions of the substrate 10.Also, the embodied design of the UD trench isolation structure 12enables the distance between adjacent regions of the substrate 10 to bedecreased (for example, a width W_(UD) of the UD trench isolationstructure 12 can be decreased to about 1 μm such as in a range of 2 μmto 3 μm) for saving the area of the substrate 10, thereby reducing thesize of the IC structure required for disposing the semiconductordevices and decreasing the manufacturing cost. Moreover, when thesemiconductor devices in some of the regions of the substrate 10 (suchas the first region A₁ and/or the second region A₂) are implemented byusing the VDMOS transistors (i.e. the source region and the drain regionrespectively positioned at the top surface and the bottom surface of thesubstrate), it enhances the heat dissipations of the semiconductordevices, thereby improving reliability of the semiconductor devicesduring operation and prolonging the operation life of the IC structurein application. Also, the manufacturing method of the embodied UD trenchisolation structure is compatible with the current fabrication process,which is suitable for mass production.

Other embodiments with different configurations of known elements in thesemiconductor device can be applicable, and the arrangement depends onthe actual needs of the practical applications. It is, of course, notedthat the configurations of figures are depicted only for demonstration,not for limitation. It is known by people skilled in the art that theshapes or positional relationship of the constituting elements and theprocedure details could be adjusted according to the requirements and/ormanufacturing steps of the practical applications.

While the disclosure has been described by way of example and in termsof the exemplary embodiment(s), it is to be understood that thedisclosure is not limited thereto. On the contrary, it is intended tocover various modifications and similar arrangements and procedures, andthe scope of the appended claims therefore should be accorded thebroadest interpretation so as to encompass all such modifications andsimilar arrangements and procedures.

What is claimed is:
 1. An integrated circuit (IC) structure, comprising:a substrate having a top surface and a bottom surface oppositely, andthe substrate comprising a plurality of regions; semiconductor devicesformed at the substrate and respectively within the plurality ofregions; an ultra-deep (UD) trench isolation structure formed in thesubstrate and surrounding peripheries of each of the plurality ofregions for isolating the semiconductor devices within different regionsof the plurality of regions; a gate oxide and a gate electrode, bothdisposed on the top surface and above the top surface of the UD trenchisolation structure; wherein the UD trench isolation structurepenetrates the substrate in its entirety by extending from the topsurface of the substrate to the bottom surface of the substrate, and alower surface of the UD trench isolation structure is exposed at thebottom surface of the substrate, wherein none of drain regions, aportion of the substrate and an insulative material layer covers thelower surface of the UD trench isolation structure; wherein theplurality of regions comprises a high-side region and a low-side regionapart from each other by the UD trench isolation structure; andperipheries of the high-side region and the low-side region aresurrounded by the UD trench isolation structure.
 2. The IC structureaccording to claim 1, wherein a depth of the UD trench isolationstructure is substantially equal to a thickness of the substrate.
 3. TheIC structure according to claim 1, wherein the UD trench isolationstructure comprises an insulating material of nitrides, oxides or both.4. The IC structure according to claim 1, wherein the plurality ofregions further comprises a first region adjacent to and electricallyconnected to the high-side region, and a periphery of the first regionis surrounded by the UD trench isolation structure.
 5. The IC structureaccording to claim 4, wherein a first vertical double-diffused metaloxide semiconductor (VDMOS) transistor is formed in the first region. 6.The IC structure according to claim 1, wherein the plurality of regionsfurther comprises a second region adjacent to and electrically connectedto the low-side region, and a periphery of the second region issurrounded by the UD trench isolation structure.
 7. The IC structureaccording to claim 6, wherein a second vertical double-diffused metaloxide semiconductor (VDMOS) transistor is formed in the second region.8. The IC structure according to claim 1, wherein the plurality ofregions further comprises a first region adjacent to and electricallyconnected to a high-side region, and a second region adjacent to andelectrically connected to a low-side region, wherein at least one of thefirst region and the second region comprises a vertical double-diffusedmetal oxide semiconductor (VDMOS) transistor, and a source region andone of the drain regions of the VDMOS transistor are positioned at thetop surface and the bottom surface of the substrate, respectively. 9.The IC structure according to claim 8, wherein the VDMOS transistor isconfigured with a planar structure and the VDMOS transistor comprisesthe gate oxide on the top surface of the substrate, the gate electrodeon the gate oxide, and a horizontal channel diffused from an edge of thesource region near the gate.
 10. The IC structure according to claim 8,wherein the VDMOS transistor is configured with a trench-gate structure,and the VDMOS transistor comprises a gate structure extending downwardlyfrom the top surface of the substrate, and the gate structure comprisesa gate in a vertical trench and an insulating layer surrounding part ofthe gate in the vertical trench, wherein a vertical channel is diffusedfrom an edge of the source region near the gate.
 11. The IC structureaccording to claim 1, wherein a depth of the UD trench isolationstructure is at least 60 μm or more.
 12. The IC structure according toclaim 1, wherein a width of the UD trench isolation structure is atleast 1 μm or more.